One of serious diseases affecting the dairy cattle is the bovine mastitis which is an infectious disease caused by bacteria and other microorganisms that have entered into the breast through the teat opening, settled and multiplied therein. However, the factors of development are so complex that the disease has not been eradicated yet. If affected by the bovine mastitis, not only the amount of milk and the quality of milk decrease but also it becomes no longer allowable, if the cattle is treated with antibiotics, to ship the milk during the period of treatment due to the probable residence of the drugs. Moreover, if the symptoms are serious and the disease cannot be cured, then the affected cattle must be eliminated causing a tremendous damage in economy to the dairy farmers.
In order to prevent the bovine mastitis at present, it is a generally employed method to dip the teats in a dipping agent (sterilizing aqueous solution) before and after the milking in the lactation period of milking. This is to sterilize the mastitis-causing bacteria adhered to the surfaces of the teat skin. It has also been attempted to reduce the area to where the mastitis-causing bacteria have adhered by adding a skin condition-improving component such as moisturizer to the dipping agent. A variety of dipping agents have been proposed chiefly for pasteurization (e.g., patent documents 1 and 2), and many products have now been placed in the market.
A method has also been widely employed according to which in the dry period of not milking the cattle, antibiotics are injected into the breast through the teat openings at the beginning of the dry period so that the mastitis-causing bacteria may die out. In the initial stage of dry period, it is considered that the antibiotics exhibit sterilizing effect to some extent and are effective in the prevention of the bovine mastitis accompanied, however, by such problems as leakage of antibiotics from the teat openings, mixing of antibiotics into raw milk at the beginning of milking after the dry period has been finished, and advent of resistant bacteria against the antibiotics if they are used for extended periods of time. There has, further, been reported that the dairy cattle are prone to be newly affected by the bovine mastitis at an increased probability in the initial stage of dry period and in the last stage of dry period before the delivery. Therefore, it cannot be said that the countermeasure is sufficient for preventing the bovine mastitis by using antibiotics.
As a means for protecting the teats of dairy cattle from the mastitis-causing bacteria, therefore, there has been proposed an art of preventing bacteria and other microorganisms from entering into the breast through the teat openings.
For instance, a patent document 3 proposes a means of “dipping the teats in a teat-sealing agent to maintain the teats in a state where a thin film is formed on the teats closing the teat openings during the period of about 2 days to about 9 days in the initial stage of dry period of cattle when they are liable to be infected with the bovine mastitis and during the period of about 2 days to about 9 days before the delivery”. By the above means, it is considered that the infection of the mastitis-causing bacteria is physically blocked, and the cattle can be prevented from being infected with the bovine mastitis. As the film-forming component in the teat-sealing agent, the patent document 3 exemplifies rubber materials such as urethane rubber, latex rubber, butadiene rubber, polyvinyl alcohol, liquid butyl rubber, liquid rubber, natural rubber, butyl rubber, nitrile rubber, chloroprene rubber, vinyl acetate rubber and the like rubbers. Namely, these rubber materials are dissolved in a solvent such as toluene or xylene, and the teats are dipped in the solution thereof (teat-sealing agent) to form a film of rubber material on the teats.
However, the film of rubber material formed by the above method cannot fully reliably adhere to the teats and tends to be easily removed from the teats. That is, the film of rubber material cannot, in many cases, maintain the teat openings closed during the above period of about 2 days to about 9 days during which the infection with the mastitis-causing bacteria must be blocked, and improvements have been desired.
A patent document 4 is proposing a teat protection material for cattle, that comprises a flexible film having water-proof property and a large stretching ratio at breakage and that is fixed by being wrapped round the teats.
In fact, however, the teat has a shape that becomes thin toward the teat opening at the end. Even if the above flexible film is wrapped round the teat, therefore, the film, in many cases, cannot be maintained to stay closely adhered to the teat opening which is the most essential part allowing to form a gap easily between the teat opening and the film. Formation of the gap causes a decrease in the degree of protecting the teat openings, as a matter of course. Moreover, the disease-causing bacteria such as germs may intrude through the gaps and, besides, the film is easily removed from the teats.